Speed control for rocking mill stands



Dec. 14, 1965 E. HELSING SPEED CONTROL FOR ROCKING MILL STANDS 2 Sheets-Shae?! Filed May 1, 1962 5 5 m TW A m/ 3 I 5 2 v 5 gw M M Q w 7 \ll 4 m 4. G r A INVENTOR. Erik f/s/mv;

Dec. 14, 1965 E. HELSING 3,222,900

SPEED CONTROL FOR ROCKING MILL STANDS Filed May 1, 1962 Fig. 2

2 Sheets-Sheet 2 SPEED coNTRoL roiz RbcKINo MILL STANDS The present invention relates to a regulating system for continuous tooling lines, such as wire or tape rolling mills, comprising at least two rolling stands.

A normal requirement with such devices is either to avoid tension in the passing material or to maintain a certain predetermined tension or tensile force between some or all the rolling stands. This is necessary if the passage of the Wire (tape, etc.) between the rolling stands is to be stable since it may otherwise easily skid at the high rolling speeds often used in modern rolling mills. During rolling a certain variation in temperature relation, cross sectional area of the rolling goods, hardness, etc., also occurs, thus causing a certain variation in reduction relations in a rolling gap and therefore a tension regulation must be arranged which at the greatest variation in one direction does not cause slack wire or tape between the rolling stands and their roller pairs and at the'greatest variation in the other direction does not cause too great tension.

Hitherto, the most usual arrangement in continuous rolling mills for rolling wire, tapes, etc. when it is desired to avoid tensile forces in the rolling goods, is an arrangement using so-called loop-regulation in some form, i.e. the material follows a crooked path between the rolling stands and the loop position deviations are measured in some way. Via some suitable conversion means this measured magnitude may influence the revolution rate of the motors of the roller pairs lying before or after. Particularly at said high rolling speeds (30 m./s. starting speed and higher in for example wire rolling mills) difficulties eventually arise with the crooked path between adjacent roller pairs. It has been found that the last wire end in wire rolling has a tendency to knot itself when it leaves one roller pair and will proceed forward, but is simultaneously dragged down by the gravity of the loop. It has been tried to solve these and other similar problems in different Ways, for example by guiding the last material end in a special path, so-called whip screen. With very high rolling speeds, however, it has been necessary to search for other rolling methods where loops are eliminated.

The invention relates to a regulating system of the above mentioned type for continuous tooling lines for solving the above mentioned problems, and is characterised in that measuring devices are arranged to measure the tensile force between two adjacent rolling stands, the output signals of the measuring devices being arranged to be fed directly or indirectly to driving means to the diiferent roller pairs with the intention of regulating the tension in the rolled goods in relation to a desired adjustable value, for example, zero. With such a regulating system the risk of knots, bends, etc. in the rolled material is substantially eliminated, thus to a great extent eliminating the risk that the material will have to be scrapped. In a preferred embodiment of the invention the tensile force is sensed in one or both directions in some or all the rolling stands, for example in connection with the rolling stands being tilted around a certain point. One type of sensing for such a purpose may be a rockable or movable rolling housing with rollers, which housing, during its movement, contacts measuring means of 3,222.5 061 Patented Dec. 14, 1965 any well-known kind, which means measure the pressure from the housing and thus the tensile force built up in the goods being rolled. There are at least two said measuring means, one contacting the housing during movements in one direction and one in the other direction. Such sensing means are shown in the Patent to Norton, No. 2,650,495. Pressure sensing means sense the position of the housing and generates a signal. The attachment between the rolling stand and the supporting base is resilient to avoid friction, and the pressure sensing means arranged on both sides of the rolling stand supports are formed so that they simultaneously act as installation support to limit the swinging movement of the rolling stand. By means of such a system the time constant will be extremely low and the regulating accuracy can be maintained at a very high standard.

Embodiments of the invention are shown in the accompanying figures where FIGURE 1 shows a continuous tooling line for wire rolling, comprising five rolling stands with respective roller pairs. FIGURE 2 shows an alternative connection for the driving motor regulation and FIGURE 3 a supplementation of the systems of FIG- URES 1 and 2.

An arbitrary roller pair in a tooling line is chosen (here for wire rolling) as base, here the rolling stand 3 (FIGURE 1) with respective roller pair 32, and the driving motor 33 for this roller pair follows a reference magnitude 600 common for the whole construction, corresponding to the production speed, suitably adjustable via a potentiometer 6000. By means of individual adjusting members 601, 602, 604, 605 for each roller pair 12, 22, 42, 52, a reference magnitude is given, suitable for the revolution rates of the driving means 13, 23, 43, 53, for the different roller pairs, so that between the roller pairs a somewhat greater tension is obtained than that for which the regulating means for tensile force (see below) is adjusted.

In the embodiment shown certain desired tensile forces are adjusted between the rolling stands and the force in the sensing means 11, 21, 31, 41, 51 of the rolling stand (which may be of the type mentioned above and schematically shown in the accompanying figures). Alterations in the tensile force may be sensed on one or both sides and a signal proportional to the sensed tensile force (single or double sided) is arranged to be emitted from the schematically shown members 11, 21, 31, 51. As mentioned the roller pair 32 in the rolling stand 3 is here chosen as base.

The revolution rate of the base roller pair 32 is sensed by means of a tachometer-generator 34, the output signal of which is fed to the input side of a current feeding member 35 for the driving motor 33, which member may consist of a direct current generator or a converter, and the output signal from 34 is suitably fed together with the reference signal 600 to a magnetization circuit or control circuit within the generator or converter respectively. The tensile force is not in the first place sensed for the base rolling stand. For the other roller pairs 12, 22, 42, 52, the revolution rate is sensed and corresponding signals are fed, as with the base roller installation 3, to current feeding members 15, 25, 45, 55 for corresponding driving members 13, 23, 43, 53. The output signals or from the devices 1151 are fed to gates 101-105, which block signals below a certain value or amplitude and transmit signals above the same value or amplitude. Such gates are of a type known in the art, consisting of two diodes and a shunt resistance, coupled to a DC polarity (i). The output signals from 101 to 501 are fed to a PI device (proportional-integralamplifie-rs, composed of an amplifier shunted by a capacitance and a resistance). The output signal from rolling track).

said gates is an integration and a proportional amplification of the input signal of the same gate. Further the tensile force signal for the rolling mill 2 is also fed to rolling mill 1 in front in the rolling direction (arrow A) (and possibly rolling mills even earlier in the The tensile force signalfo'r the rolling mill 4 is also fed to the current feeding means for the rolling mill 5 and possibly subsequent rollin'g'r'nills.

Alternatively, the tensile force signal (broken lines in FIGURE 1) may be fed from the base mill to the angle curve device 201 of the previous rolling mill 2, from the rolling mill 2 to the angle curve 'device 101 of the rolling mill 1, etc., and from the rolling mill 4 to the angle curve device 501, etc.

With the desired tensile force at zero between two adjacent rollers pairs the angle curve device is taken away but not the limitation before the PJ-link, and thev tensile force signal is "fed via the limitation and PJ-link or the input side of the current feeding 'means.

In all cases the rolled goods must be allowed to pass in a straight track between adjacent roller pairs.

The regulating system according to FIGURE '1 (complete alternative) operates 'in the following way:

When the rolled material comes from the base pair 32 to the pair 42, it may be assumed that the tensile force in the material between these pairs 32, 42 is greater than the desired value. Assuming further that with a're'sultant tensile force on the pairs 42 and 52 respectively, which tries to draw the rolling stands 41 and 51 respectively, these signals give the order to decrease the revolution rates from the driving means 43 and 53 to the pairs 42 and 52 respectively. It should be observed that an order to decrease, the revolution rate must reach both the 'pairs 42 and 52 so that tensile force discrepancies shall not occur between the pairs 42 and '52 at regulation between the pairs 32 and 42.

Because of the angle curve devices, the PI-links will obtain signals first when a certain value is exceeded for the signal from the means 11, 21, 31, 41 and 51, etc., and this limit value should suitably be adjustable. The regulation will afterwards regulate so that the tensile force between the rolling stands is constant (possibly zero) during rolling.

, When regulating the tensile force zero the angle curve devices are suitably replaced by a direct connection in order to obtain on the input side of the current feeding member a signal proportional to alterations from tensile force zero. Of course, any of the rolling mills in the line may be chosen as base. Feeding of the rolling and tensile force signals to rolling mills lying before or after in rolling direction may be altered in relation to this.

FIGURE 2 shows an alternative connection for driving motor regulation. From the tachometer-generators 14, 24, 34, 44, 54 (FIG. 1) come the signals proportional to the rolling speeds, to the input side of the current feeding members (15, 25, 35, 45, 55) in the same way as shown in connection with FIGURE 1. From the tensile force sensing members comes in the same way a signal proportional to the tensile force (or tensile force alteration), Which is added to a tensile force reference signal 700 and fed to a PJ- or other link (amplifier) from which a signal together with the just mentioned speed signal and reference signals for production speed 600, 601, 602, 604, 605, is fed to the input side of the current feeding means and a regulation similar to that for the system according to FIGURE 1 may be obtained.

In FIGURE 3 is shown a supplementation of the system according to FIGURES 1 or 2. Output signals from the member 41 for the tensile force measurement with a certain minimum amplitude are fed via an angle curve device 411 and possibly a limiting device 412 to members for controlling a screw motor 46 for the mill screw,

and via 461 a setting signal for rolling gap alterations may be fed to the screw motor. The speed of the screw motor is sensed in a suitable way and this last mentioned signal may also be fed to the screw motor. By means of this arrangement with screw motor regulation for greater output signals from 41, etc., the desired rolling gap adjustment can be maintained and in the above Way precision regulation of the driving means 43 for the rollers 42 is obtained and other roller pairs in the chain can be regulated in the same way. The dead zone, i.e. the blocked area, from 401 must be smaller (precision regulation) than the dead zone 411 (rough regulation), preferably :0.

The amplifiers 402, and 412 have limits and by means of suitable adjustment, help to limit the range for alterations in the revolution rate of the rolling motor 43. Simultaneously, the mill screw motor 46 receives a speed substantially proportional to the error signal.

The above given embodiments may be varied in many ways within the scope of the invention. The different elements in the system could, for example, be rep'laced by others known within the regulating and amplifying technique.

What is claimed is:

1. Rolling mill for thin goods comprising a roller train with a first base rolling mill and at least second and third other mills, each mill comprising a housing, driving means and at least one pair of working rollers mounted in said housing, means mounting at least the housings of said second and third mills for movement in relation to the ground, at least said second and third mills being provided with means responsive to movement of the housings in two opposite directions for measuring the tensile force upon the housing resulting from the pull of the rolled goods and for producing an output signal, means to adjust the roll speed of the base mill to a desired value, means for adjusting the roll speeds of the second and third mills to other values, so as to produce a certain tensile force in the rolled goods from the adjacent mills between adjacent housings, and means to feed the output signal of the measuring means upon movement of the corresponding housing at least indirectly to the driving means of the same mill.

2 Rolling mill for thin goods comprising a roller train with a first base rolling mill and at least second and third other mills, each mill comprising 'a housing, driving means and at least one pair of working rollers mounted in at least the housings of said second and third mills, means mounting said housings for movement in relation to the ground, at least said second and third mi-lls being provided with means responsive to movement of the housings in two opposite directions for measuring the tensile force upon the housing resulting from the pull of the rolled goods and for producing an output signal, means to adjust the roll speed of the base mill to a desired value, means for adjusting the roll speeds of the second and third mills to other values, so as to produce a certain tensile force in the rolled goods from the adjacent mills between adjacent housings, said second and third mills to feed the output signal of the measuring means upon 'movement of the corresponding housing of that one of the second and third mills nearer to the base mill to the driving means of the other of said second and third mills.

3. Rolling mill in accordance with claim 1, said second and third mills being located on the same side of the base mill, and means to feed the output signal of the measuring means upon movement of the corresponding housing of that one of the second and third mills nearer to the base mill to the driving means of the other of said second and third mills.

4. In a rolling mill in accordance with claim 1, means to measure the roll speed, of at least one of said mills to produce a second output signal, and means to feed said second output signal back to the driving means of the corresponding mill.

5. In a rolling mill in accordance with claim 4, means to combine said output signals.

6. In a rolling mill in accordance with claim 4, gate means for blocking signals below a certain value and transmitting signals above the same value, and means to feed the first output signal through said blocking means.

7. In a rolling mill in accordance with claim 1, in which each mill includes a screw-down motor, means to feed the signal from the measuring means at least indirectly to the screw motor of the corresponding mill, a gate means blocking for signals below a certain value, said signal being transmitted over said gate means.

8. Rolling mill for thin goods comprising a roller train including a first rolling mill and at least second and third other mills, each of these mills comprising a housing, driving means and at least one pair of working rollers mounted in said housing, means mounting at least the housings of said second and third mills for movement with respect to the ground, first means to measure the roll speed in the base mill, means to feed the output signal of said measuring means to the driving means of said base mill, means to feed to the driving means of said base mill a speed reference signal, at least the housings of the second and third mills being provided with second measuring means responsive to movement of the housings in two opposite directions for measuring the tensile force upon the housing resulting from the pull of the rolled goods from the adjacent mills, means for feeding the output signal of said second measuring means at least indirectly to the driving means of the same mill and to at least the driving means of one mill further from the base mill, third means to measure the rolling speeds of the second and third mills, means to feed the output signals of said third measuring means to the driving means of the same mill, means to feed to said last driving means a speed reference signal, the value of the speed reference signals of all other mills being different from the reference signal of the base mill.

OTHER REFERENCES Control Engineering: pages 116, 117, September 1956. Control Engineering: pages 7480, October 1957.

CHARLES W. LANHAM, Primary Examiner.

5 WILLIAM J. STEPHENSON, Examiner. 

1. ROLLING MILL FOR THIN GOODS COMPRISING A ROLLER TRAIN WITH A FIRST BASE ROLLING MILL AND AT LEAST SECOND AND THIRD OTHER MILLS, EACH MILL COMPRISING A HOUSING, DRIVING MEANS AND AT LEAST ONE PAIR OF WORKING ROLLERS MOUNTED IN SAID HOUSING, MEANS MOUNTING AT LEAST THE HOUSINGS OF SAID SECOND AND THIRD MILLS FOR MOVEMENT IN RELATION TO THE GROUND, AT LEAST SAID SECOND AND THIRD MILLS BEING PROVIDED WITH MEANS RESPONSIVE TO MOVEMENT OF THE HOUSINGS IN TWO OPPOSITE DIRECTIONS FOR MEASURING THE TENSILE FORCE UPON THE HOUSING RESULTING FROM THE PULL OF THE ROLLED GOODS AND FOR PRODUCING AN OUTPUT SIGNAL, MEANS TO ADJUST THE ROLL SPEED OF THE BASE MILL TO A DESIRED VALUE MEANS FOR ADJUSTING THE ROLL SPEEDS OF THE SECOND AND THIRD MILLS TO OTHER VALUES, SO AS TO PRODUCE A CERTAIN TENSILE FORCE IN THE ROLLED GOODS FROM THE ADJACENT MILLS BETWEEN ADJACENT HOUSINGS, AND MEANS TO FEED THE OUTPUT SIGNAL TO THE MEASURING MEANS UPON MOVEMENT OF THE CORRESPONDING HOUSING AT LEAST INDIRECTLY TO THE DRIVING MEANS OF THE SAME MILL. 